DESCRIPTION: (Applicant's Abstract) The goal of this project will be to institute Phase I-II trials of antisense oligodeoxynucleotides (AS ODN) targeting the c-myb protooncogene in acute and chronic myelogenous leukemia. The specific aims of the project are as follows: 1. Determine the pharmacokinetics of sAS ODN in patients with specified hematologic malignancies. Initial sAS ODN treatment protocols have been developed based on available in vitro and in vivo efficacy and pharmacokinetic data. Uptake, distribution, and clearance of sAS ODN from various fluid and organ compartments as well as from bone marrow will be studied using HPLC and hybridization techniques. Data will be analyzed as a function of time, dose, and schedule of drug administration in order to facilitate development of rational drug delivery and treatment protocols. 2. Determine the toxicity and clinical efficacy of sAS ODN. Two broad categories of toxicity may be envisioned. The first is the direct result of perturbing the targeted gene's function. The second category relates to toxicities which are not gene specific but rather inherent to phosphorothioate compounds. Monitoring of major organ system function by physical examination, imaging, blood chemistries, blood cell counts and growth of hematopoietic cell colony forming units in vitro will be carried out. Toxicities will be monitored, typed, and correlated with the pharmacokinetic data to be gathered in the first Specific Aim. This should allow optimization of the sAS ODN's therapeutic index. Toxicity data will then be used to develop subsequent trials investigating alternative treatment doses and schedules. Phase I trials in myeloid leukemia will be initiated using the results. 3. Determine the pharmacodynamics of inhibiting the functions of targeted protooncogenes. It remains to be established in vivo whether degree of ODN uptake correlates with changes in the target's expression and consequent changes in tumor cell growth and/or malignant phenotype at the gross cellular level. Accordingly, the applicant will first correlate uptake of sAS ODN with dynamic changes in targeted gene expression at both the mRNA and protein levels. Examination of effects of the ODN on "control" gene expression will also be carried out to determine if the ODN's effects are indeed sequence specific and, therefore, true antisense effects. In so doing he will test the hypothesis that fundamental changes in the malignant cells' behavior can be correlated with the induced changes in targeted protooncogene expression. He will then explore potential sub- cellular mechanisms for these changes by identifying selected phenotypic/morphologic changes that occur in leukemic cells exposed to the c- myb antisense ODN. These studies are important since they will begin to explain why malignant cells are apparently more sensitive to the ODN than their normal counterparts. Finally, the applicant also intends to explore potential mechanisms of resistance to the ODN by examining ODN uptake, trafficking, efflux, and rates of target gene transcription in patients who have initially responded to the ODN but have subsequently relapsed.